A decision algorithm for discarding frames is disclosed. A method is disclosed including the application of rules which results in the limited use of the Partial Packet Discard (PPD) method and results in the ATM cells which are not assigned to a frame not being discarded. According to the described Early Packet Discard (EPD) system, all the cells in a frame, from the first cell to the last cell, are removed from an ATM communications device upon arrival in a queue. The EPD system results in no residual cells remaining from a damaged frame or from a frame which is to be removed for other reasons. Additionally, each connection has a Maximum Frame Size (MFS), which is measured in cells and depends on the connection. Thus, increased space is available for other ATM cells.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method for removal of ATM cells from an ATM communications device, comprising: assigning a plurality of ATM cells to a common frame; storing said plurality of ATM cells in connection-specific queues; removing all newly arriving cells with the exception of a first and a last ATM cell in a frame, with a first algorithm; removing all of the ATM cells in a frame, from a first to a last cell, on arrival in a queue from said ATM communications device; defining a plurality of ATM cells as not being assigned to a frame; indicating, by a user, at a start of a transmission process, a maximum number of ATM cells per frame; transmitting ATM cells, according to said maximum number of ATM cells per frame; ensuring that said cells which are not assigned to a frame are still included in said queue so that they are not discarded; discarding an associated frame when said maximum number of ATM cells per frame is exceeded, or, if said discarding is not possible, utilizing said first algorithm.
2. The method as claimed in claim 1 , further comprising excluding from discarding cells which are not recognized as frame cells.
3. The method as claimed in claim 1 , further comprising defining a connection-specific length for said queue.
4. The method as claimed in claim 1 , further comprising defining, per connection, a constant magnitude, which is a measure of said maximum number of ATM cells per frame.
5. The method as claimed in claim 1 , further comprising utilizing a number of cells which are not to be discarded on a connection-specific basis, said number of cells being the number of cells for a particular connection which have arrived since a last end of the frame for said particular connection.
6. The method as claimed in claim 1 , further comprising the stop of limiting, per queue, a number of cells which are not to be discarded and are allowed in said queue at a specific time as a parameter which is independent of said queue (N_exclusion_cells_max).
7. The method as claimed in claim 1 , further comprising calculating, per connection, a number of cells which are not to be discarded which number results from a difference between N_exclusion_cells_max minus a present number of excluded cells in said queue.
8. The method as claimed in claim 1 , further comprising: reserving a predetermined number of cell memory location per queue (N_exclusion_cells_max) for cells which are not to be discarded; and prohibiting access of user-related cells to some of said queue locations.
9. The method as claimed in claim 1 , further comprising: comparing a length of a queue to a value S_PPD_ 0 , said value being independent of a connection, and storing no high-priority cells per connection if said length of said queue for said connection is equal to said value S_PPD_ 0 .
10. The method as claimed in claim 1 , further comprising: inhibiting use of said first algorithm in a situation where high-priority frames do not exceed a predetermined length.
11. The method as claimed in claim 1 , further comprising: reserving a specific amount of buffer-storage space for high-priority cells per connection; and prohibiting access of low-priority cells to said buffer-storage space.
12. The method as claimed in claim 1 , further comprising the stop of preventing storage of high-priority cells for a connection if a length of a queue for a given connection is of at least a further size S_PPD_ 1 =S_EPD_ 1 +MFS+N_exclusion_cells_max, in which S_EPD_ 1 and N_exclusion_cell_max are independent of said connection and MFS is dependent on said connection.
13. The method as claimed in claim 1 , further comprising: completely discarding high-priority frames if, on arrival of a first cell of a given connection with less than [[MES]] MFS+N_exclusion_credits, cell memory space is available in a connection-specific queue or said connection-specific queue exceeds a threshold S_EPD_ 0 and a buffer-storage filling at the same time indicates that high-priority frames should be discarded.
14. The method as claimed in claim 1 , further comprising the step of discarding high-priority frames using said first algorithm if, on arrival of a cell which is neither a first nor a last cell in a frame, a connection-specific queue only provides space for at most 1+N_exclusion_credits_cells or said connection-specific queue exceeds a connection-specific threshold value S_EPD_ 0 and a status of a buffer store indicates that high-priority frames should be discarded, or if said frame is longer than said user-indicated maximum number of ATM cells per frame.
15. The method as claimed in claim 1 , further comprising completely discarding: low-priority frames if, on arrival of a first cell of a connection, a length of a queue for said connection is longer than a value S_PPD_ 1 minus N_exclusion_credits or if said length of said queue is longer than a value S_EPD_ 1 and a status of a buffer store indicates that low-priority frames should be discarded.
16. The method as claimed in claim 1 , further comprising: discarding some low-priority frames for a connection using said first algorithm if, on arrival of a cell which is neither a first nor a last cell in a frame, a length of a queue for said connection is greater than S_PPD_ 1 minus N_exclusion_credits minus 1 or said length of said queue is greater than S_EPD_ 1 and a status of a buffer store indicates that low-priority frames should be discarded, or if said frame is longer than said maximum number of ATM cells per frame.
17. The method as claimed in claim 1 , wherein a queue-specific value S_EPD_ 0 is greater than S_PPD_ 1 and less than S_PPD_ 0 -MFS-N_exclusion_cells_max.
18. The method as claimed in claim 1 , further comprising: preventing, if a buffer filling level is low, high-priority frames whose first cell has been accepted and whose frame length does not exceed said maximum number of ATM cells per frame from using said first algorithm.
19. The method as claimed in claim 1 , further comprising: preventing if a buffer filling level is low, low-priority frames whose first cell has been accepted and whose frame length does not exceed said maximum number of ATM cells per frame from using said first algorithm.
20. The method as claimed in claim 1 , further comprising: preventing simultaneous setting of an EPD_flag and a FPD_flag.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
February 26, 1999
January 25, 2005
Browse 5M+ US patents with plain-English claim translations and AI-generated analysis.